铁路货车制动管焊接残余应力测试与焊接组装工艺改进

Testing of Residual Stress on Welded Brake Pipe and Improvement of Welding and Assembly Process for Railway Freight Cars

应用钻孔法对脱轨阀制动管进行了焊接残余应力测试,测试结果表明原焊接工艺条件下,由于制动管管身端部在焊接热的作用下伸长变形受到限制,加剧了焊缝处的径向收缩变形,导致焊趾处产生较大的残余拉应力,在外载荷的二次应力作用下,制动管焊趾处承受了较大的拉应力,增加了制动管焊缝处的疲劳破坏几率。通过对焊接组装工艺改进,降低了制动管焊后焊趾处的残余拉应力,可有效提高制动管疲劳寿命。

Hole-drilling method has been applied for testing of residual stress on the welded derailment valve brake pipe.Results of the test indicate that under original welding conditions the radial shrink deformation to the weld has been deteriorated due to restriction to lengthwise deformation arising from welding heat at the end of the brake pipe,so that substantial residual tensile stress has been generated at weld toe.Under the secondary stress from external loads,such substantial tensile stress has been received at the weld toes,increasing the probability of fatigue damage to the weld on brake pipe.Improvement of welding and assembly process will reduce the residual tensile stress on the weld toe after welding of the brake pipe,and effectively improve the fatigue life of the brake pipe.